Stator for rotary electric machine and rotary electric machine using same

ABSTRACT

The wire  30  forming the stator winding  20  includes the in-slot portions  40  to be disposed in the slots  14  and  15  of the stator core  12  and the turned portions  42  connecting the in-slot portions  40  disposed in the circumferentially different slots  14  and  15 . The turned portions  42  formed on axial opposite end sides of the stator core  12 . The crank portion  44  which does not twist is formed at substantially the center of the turned portion  42 . Steps are fanned at sections of the turned portion  42  which protrude outside the stator core  12  from the slots  14  and  15 . Further, the turned portion  42  of the wire  30  also has two steps  48  formed between the substantially central crank portion  44  and each of the steps  46  formed at the protruding sections of the turned portion  42.

TECHNICAL FIELD

The present invention relates to a stator for a rotary electric machineand a rotary electric machine using the same.

BACKGROUND ART

What are disclosed in patent documents 1 and 2 as rotary electricmachines working as an electric motor and an electric generator or usedonly as the electric motor or the electric generator. In both the patentdocuments 1 and 2, so-called segment conductors (SC) configured in theform of substantially U-shape are disposed in slots of a stator core.Open ends of the segment conductors are electrically joined to makestator windings.

However, in the patent document 1, the segment conductor is twisted atthe center of the turned portion to insert it into the circumferentiallydifferent slots, thus giving rise to the problem that the height h ofportions of the stator windings 310, as illustrated in FIG. 24, whichprotrude outside axial opposite ends of the stator core 300 (portions ofthe stator windings protruding from the stator core in the axialdirection will be referred to as coil ends below) is great, so that thestator windings 310 overhang greatly from the stator core 300. Asillustrated in FIG. 25, the height h of the coil ends depends upon theinterval between the slots 302 in which the segment conductors 320 aredisposed and a bend angle of the segment conductors 320 at the coilends. The bend angle of the segment conductor 320 depends upon thethickness thereof and a coil interval. In other words, the height h ofthe coil ends depends upon the height of a triangle which has a basethat is an interval between the slots 302 in which the segment conductor320 is disposed and a basic angle that is the bend angle of the segmentconductor 320.

In the patent document 2, as illustrated in FIG. 25, the crank-shapedportion 322 which does not twist is formed at substantially the centerof the turned portion of the segment conductor 320 to flatten thecenter, thereby decreasing the height of the coil ends.

However, if interval between the slots 302 in which the segmentconductor 320 is disposed and the thickness of the segment conductor 320are identical between the patent documents 1 and 2, the triangle definedby the segment conductor 320 on the coil end will be the same in size ofthe base and basic angle thereof between the patent documents 1 and 2,Therefore, there is a limitation of decreasing the height of the coilends even when the segment conductors of the patent document 2 are used.

Patent Document 1: Japanese Patent First Publication No. 11-285216

Patent Document 2: Japanese Patent First Publication No. 2003-18778

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

The invention was made in order to solve the problem. It is an object todecrease the height of coil ends of a stator winding which protrude froma stator core.

Means for Solving Problem

In the invention, as recited in claim 1, steps which extend along an endsurface of a stator core are formed at sections of turned portionsprotruding from slots. This causes the interval between the protrudingsections of the turned portion to be smaller than the interval betweenthe slots in which wire is disposed, thus resulting in a decrease inshape of the wire overhanging from the stator core which leads to adecrease in height of the coil ends.

In the invention, as recited in claim 2, the steps which extend alongthe end surface of said stator core are formed at all the sections ofthe turned portion protruding from the slots. This results in a decreasein overall configuration of the coil ends protruding from the statorcore.

In the invention, as recited in claim 3, the length of the protrudingsections of the turned portions along the end surface of the stator coreis smaller than or equal to the interval between the slots adjacent inthe circumferential direction. This avoids the interference of theprotruding sections of the turned portion with the turned portionsprotruding from the circumferentially adjacent slot, thus eliminatingthe need for increasing the height of the coil ends or the radial widthof the coil ends in order to avoid the interference.

In the invention, as recited in claim 4, the turned portions are shapedstepwise to have the steps, which are parallel to the end surface of thestator core, in an axial direction of said stator core. The plurality ofsteps, therefore, decrease the height of the coil ends further.

In the invention, as recited in claim 5, the length of all the stepsparallel to the end surface of the stator core is smaller than or equalto the interval between the slots adjacent in the circumferentialdirection. This avoids the interference of the protruding sections ofthe turned portion with the turned portions protruding from thecircumferentially adjacent slot, thus eliminating the need forincreasing the height of the coil ends or the radial width of the coilends in order to avoid the interference.

In the invention, as recited in claim 6, if the number of phases of thestator windings is k, and the number of the slots for each phase perpole of a rotor having a plurality of magnetic poles differentalternately in the circumferential direction is n, the number of thesteps formed at the turned portion is k×n. If the number of phases ofthe stator windings is k, and the number of the slots for each phase perpole of the rotor is n, a total number of the slots per pole in whichthe stator windings of circumferentially adjacent k-phases are woundwill be k×n. The wire extending over the circumferentially differentslots is, therefore, disposed in the slots which are located away fromeach other by k×n slots. It is, therefore, necessary to have the k×nsteps at the turned portion in order to avoids the interference betweenwires extending from the circumferentially adjacent slots. Theinterference between the wires is avoided by and the height of the coilends is decreased by forming the k×n steps.

As recited in claim 7, the turned portions may have a crank-shaped crankportion formed at a location farthest away from the stator core.

In the invention, as recited in claim 8, the crank portion is formed inparallel to the end surface of the stator core. This results in adecrease in height of the turned portion of the wire extending outsidethe stator core as compared with when the turned portion is twisted atsubstantially the middle thereof, which leads to a decrease in height ofthe coil ends.

In the invention, as recited in claim 9, the crank portion is shifted ina radial direction of the stator core by the width of the wire. Thisenables the multi-phase stator windings to be made by shifting the wiresin the radial direction by the width thereof and winding them withoutany clearance. This permits the radial width of the multi-phase statorwindings to be decreased. The structure in which the wires are shiftedby the width also includes that in which they are shifted byapproximately the width.

In the invention, as recited in claim 10, each of the turned portions islaid to overlap a circumferentially adjacent one of the turned portionsin the axial direction. This results in a decrease in height of the coilends.

In the invention, as recited in claim 11, the turned portion is shapedstepwise to have an axial distance between the crank portion and anuppermost step that is one of the steps defining a stepwise shape whichis farthest from the stator core in the axial direction is longer thanthe axial distance between the steps. This avoids the interference ofone of the turned portions overlapping another one.

In the invention, as recited in claim 12, the crank portion is laid toaxially overlap the uppermost step of a circumferentially adjacent oneof the turned portions. This results in a decrease in height of the coilends without any interference.

In the invention, as recited in claim 13, distances between the steps ofthe turned portion is equivalent to a height of the wire, thus avoidingthe presence of a clearance between the phase windings at the steps whenone of the turned portions overlaps another one in the axial direction.The structure in which the distances between the steps are equivalent tothe height of the wire includes that in which the distances aresubstantially equal to the height of the wire.

As recited in claim 14, the wire may have a rectangular section.

In the invention, as recited in claim 15, the wire is formed to continueover an entire circumference of the stator core, thus minimizingelectric connections between the wires. This results in a decrease inproduction cost of the multi-phase stator windings and minimizesoccurrence of failure of the electric connections arising from corrosionthereof.

In the invention, as recited in claim 16, the wire has a conductor andan insulating film wrapped about the conductor, the insulating filmhaving a thickness of 100 to 200 μm. In this case, the outer peripheryof the conductor of the wire is covered with the insulating film of 100to 200 μm in thickness, thus eliminating the need for interleavinginsulating sheet between the wires in order to ensure the insulationtherebetween.

In the invention, as recited in claim 17, the insulating film has aninner layer and an outer layer covering the inner layer. The outer layeris lower in glass-transition temperature than the inner layer.Therefore, the heat produced in the rotary electric machine will causethe outer layer to be solidified earlier than the inner layer, so thatthe hardness of the surface of the outer layer is increased, therebyproviding the scratch resistance to the wire 30. This ensures theinsulation of the wires subjected to machining to form the steps at theturned portions.

In the invention, as recited in claim 18, the wire has a fusing materialcovering an outer periphery of the insulating film. The fusing material,as referred to herein, is material which will fuse when heated and besolidified when cooled. The wires disposed in the same slot arethermally bonded through the fusing material, thus causing the wires inthe same slots to be integrated to improve the mechanical strength ofthe wires in the slots.

Usually, copper is used in conductors of the rotary electric machine inorder to decrease the electric resistance. This is because the use ofcopper results in a relatively small in electric resistance.

In contrast to this, in the invention, as recited in claim 19, theconductor of the wire is made of aluminum. The height of the coil endsis, as described above, decreased to decrease the shape of the wire as awhole, thus permitting the same electric resistance as in copper to beensured in use of aluminum. The use of aluminum soften the wires morethan in the use of copper, thus facilitating machining of the wires.

While the invention of the stator of the rotary electric machine wasdescribed, it may be, as recited in claim 2Q embodied as a rotaryelectric machine equipped with the stator, as described above. In thiscase, the same effects as described above are provided.

In the invention, as recited in claim 21, all the turned portions havethe steps parallel to the end surface of the stator core. This permitsthe height of the coil ends to be decreased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(A) is a perspective view which shows the shape of wire in thefirst embodiment;

FIG. 1(B) is a perspective view which shows a stator winding woundaround a stator core;

FIG. 2(A) is a sectional view of wire;

FIG. 2(B) is a sectional view of wire;

FIG. 3(A) is a perspective view which shows a stator;

FIG. 3(B) is an illustration of a stator, as viewed from a lateraldirection;

FIG. 4(A) is a perspective view which shows an input portion and aneutral point of a stator winding;

FIG. 4(B) is an illustration, as viewed from a B-direction in FIG. 4(A);

FIG. 5 is a schematic view which shows the shape of a coil end of wire;

FIG. 6 is a schematic view which shows magnetic poles and the structureof slots of a rotary electric machine;

FIG. 7 is an explanatory view which shows the shape of coil ends for onephase;

FIG. 8 is a specification view of windings for one phase;

FIG. 9(A) is a perspective view which shows the shape of wire in thesecond embodiment;

FIG. 9(B) is a perspective view which shows a stator winding woundaround a stator core;

FIG. 10 is a view which shows the structure of a rotary electric machineaccording to the fourth embodiment;

FIG. 11 is a perspective view which shows a coil of a rotary electricmachine of the fourth embodiment;

FIG. 12 is a view which shows a core of a stator of a rotary electricmachine of the fourth embodiment;

FIG. 13 is a view which shows core segments constituting a core of astator of a rotary electric machine of the fourth embodiment;

FIG. 14 is a sectional view which shows the structure of each phasewinding constituting a coil of a rotary electric machine of the fourthembodiment;

FIG. 15 is a which shows connections of a coil of a rotary electricmachine of the fourth embodiment;

FIG. 16 is a view which shows turned portions of a stator of a rotaryelectric machine of the fourth embodiment;

FIG. 17 is a view which shows the interference at turned portions;

FIG. 18 is a view which shows connections of a coil of a rotary electricmachine of the fourth embodiment;

FIG. 19 is a view which shows U-phase connections of a coil of a rotaryelectric machine of the fourth embodiment;

FIG. 20 is a view which shows an assembly of stator windings forming acoil of a rotary electric machine of the fourth embodiment;

FIG. 21 is a view which shows U-phase connections of a coil of a rotaryelectric machine of the fourth embodiment;

FIG. 22 is a view which shows locations where windings of a rotaryelectric machine are to be inserted into slots in the fourth embodiment;

FIG. 23 is a view which shows locations where windings of a rotaryelectric machine are to be inserted into slots in the fourth embodiment;

FIG. 24(A) is a perspective view which shows a conventional stator;

FIG. 24(B) is an illustration of a stator, as viewed from a lateraldirection; and

FIG. 25 is a schematic view which shows the shape of a coil end ofconventional wire.

DESCRIPTION OF REFERENCE NUMBERS

10: stator, 12: stator core, 13: end surface 14, 15: slot 20: statorwinding 30: wire 32: conductor 34: inner layer 36: outer layer 37:fusing material 40: in-lost portion 42: turned portion 44: crank portion46: step 48: step 50: input portion 52: neutral point 54: connectingportion 60: rotor 70: wire 72: in-slot portion 74: turned portion 76:crank portion 78: step 300: stator core 302: slot 310: stator winding320: segment conductor 322: crank-shaped 330: turned portion portion401: rotary electric 420: rotary shaft machine 430: stator core 431:slot 432: core segment 440: winding 441: conductor 442: insulatingcoating 442a: inner layer 442b: outer layer 443: in-slot portion 444:turned portion 444A: crank 444B: uppermost step 444C: second step 444D:third step 448: fusing material

BEST MODES OF THE INVENTION

Embodiments of the invention will be described below based on drawings.

First Embodiment

A stator of the first embodiment of the invention is shown in FIG. 3.The stator 10, as illustrated in FIG. 3, is used in, for example, rotaryelectric machines working as an electric motor and an electric generatorfor vehicles. The stator 10 has a rotor 60 (see FIG. 6) retained insidean inner periphery thereof to be rotatable. The rotor 60 has a pluralityof permanent magnets arrayed on an outer circumference thereof facing aninner circumference of the stator 10. A stator core 12 is made ofannular magnetic steel plates which have a given thickness and arestaked in an axial direction. The stator core 12, as can be seen fromFIG. 1, has a plurality of pairs each consisting of slots 14 and 15extending in the axial direction and located adjacent in acircumferential direction. The pairs are arrayed at an inner peripheralside in the circumferential direction of the stator core 12. Statorwindings 20 are three-phase windings each of which is disposed in thepair of slots 14 and 15 arrayed adjacent in the circumferentialdirection. The stator windings 20 are disposed, each phase in one of thethree pairs of slots 14 and 15 which are located adjacent in thecircumferential direction.

Each of wires 30 of the stator windings 20 is, as illustrated in FIG.2(A), made of a copper conductor 32 and an insulating film wrapped aboutthe conductor 32 to insulate the conductor 32 electrically. Theinsulating film includes an inner layer 34 and an outer layer 36. Theinner layer 34 covers the outer periphery of the conductor 32. The outerlayer 36 covers the outer periphery of the inner layer 34 fully. A totalthickness of the insulating film including thicknesses of the inner andouter layers 34 and 36 is 100 μm to 200 μm. The use of the insulatingfilm having a thickness of 100 μm or more ensures the insulation betweenthe wires 30 even when used in high-voltage rotary electric machinessuch as automotive drive motors. The use of the insulating film having athickness of 200 μm or less ensures the space factor of the stator. Sucha great thickness of the insulating film made up of the inner layer 34and the outer layer 36 eliminates the need for insulating the wires 30electrically from each other using insulating paper.

The outer layer 36 is made of insulating material. The inner layer 34 ismade of insulating material such as thermoplastics resin which is higherin glass-transition temperature than the outer layer 36 or polyamide.Therefore, when subjected to heat, as produced in the rotary electricmachine, the outer layer 36 is solidified earlier than the inner layer34, so that the hardness of the surface of the outer layer 36 will beincreased, thereby providing the scratch resistance to the wire 30. Thisensures the insulation of the wires 30.

Further, the wire 30 of the stator winding 20, as illustrated in FIG.2(B), has the insulating film which is made up of the inner layer 34 andthe outer layer 36 and covered at the outer periphery thereof withfusing material 37 such as epoxy resin, thereby causing the fusingmaterial 37 to melt earlier than the insulating film when subjected tothe heat generated in the rotary electric machine, so that the wires 30disposed in the same slot 14 are thermally bonded to each other throughthe fusing materials 37. The windings 30 in the same slot 14 are,therefore, change into a one-piece winding, thus resulting in anincrease in mechanical strength of the wires 30 in the slots 14. Thewires 30 may alternatively be made not to be covered with the fusingmaterial 37.

The wire 30 includes, as illustrated in FIG. 1, in-slot portions 40 tobe disposed in the slots 14 and 15 of the stator core 12 and the turnedportions 42 which extend from the slots 14 and 15 outside the statorcore 12 and connect between the in-slot portions 40 respectivelydisposed in the slots 14 and 15 arrayed in the circumferentialdirection. The wire 30 is wound around the stator core to form thestator winding 20. The turned portions 42 are formed on both axial sidesof the stator core 12. The turned portion 42 has formed on asubstantially middle thereof a crank portion 44 which is not twisted.The crank portion 44 is made to have a cranked shape at a section of theturned portion 42 which is farthest away from the stator core andextends in parallel to the end surface 13 of the stator core 12. Theamount of offset of the crank portion 44 provided by the form of acranked shape is substantially within the width of the wire 30, therebyenabling the turned portions 42 of the radially adjacent wires 30 to bewound tightly. This results in a decrease in radial width of the coilends, thus avoiding the overhanging of the stator windings 20 in theradial direction.

Protruding sections of the turned portion 42 protruding outside thestator core 12 from the slots 14 and 15 have steps 46 oriented to theslots, through which the wire 30 extends, along the end surface 13 oneither axial side of the stator core 12. This causes the intervalbetween the protruding sections of the turned portion 42 of the wire 30,as illustrated in FIG. 5, protruding from the slots 14 or 15, in otherwords, the base of a triangle, as defined by the turned portion 42, tobe smaller than the interval between two of the slots 14 or 15 in whichthe wire 30 is disposed, thus resulting in a decrease in height h of thecoil end. The steps 46 which extend along the end surface 13 on theaxial ends of the stator core 12 are formed at the protruding sectionsof all the turned portions 42, thus resulting in a decrease in overallshape of the wire 30.

If the length of the steps 46 which extend along the end surface 13 ofthe stator core 12 is defined as d1, and the interval between adjacenttwo of the slots in the circumferential direction is defined as d2, arelation of d1≦d2 is met. This avoids the physical interference of thesteps 46 of one of the wires 30 with the other wires 30 protruding fromthe circumferentially adjacent slots 14 or 15 without need forincreasing the height of the coil ends in the axial direction of thestator core 12 or the width of the coil ends in the radial direction ofthe stator core 12, thus avoiding an increase in width of the coil endsin the width-wise direction thereof and resulting in a decreased, heightof the coil ends. The decrease in width of the coil ends in thewidth-wise direction also avoids the overhanging of the stator windings20 in the radial direction.

The wire 30 also has two steps 48 formed between a crank portion 44 at asubstantially middle of the turned portion 42 and each of the steps 46formed at the protruding sections of the turned portion 42.Specifically, the turned portion 42 of the wire 30 on one of the endsurfaces 13 of the stator core 12 opposed in the axial direction thereofhas a total of six steps and one crank portion. This results in adecrease in height h of the turned portions 42 as compared with atriangular turned portion 330 having no steps and the crank portion. Thesteps 48 are identical in configuration with the steps 46 and extendsubstantially parallel to either of the end surfaces 13 of the statorcore 12. Specifically, the turned portion 42 of the wire 30 is shapedstepwise to have a plurality of steps on both sides of the crank portion44 in the axial direction of the stator core. The length of each of thesteps 48 parallel to the axial opposite end surfaces 13 of the statorcore 12 is smaller than or equal to the interval betweencircumferentially adjacent two of the slots 14 and 15. This avoids theinterference of the protruding sections of the turned portion 42 withthe turned portions 42 protruding from the circumferentially adjacentslots 14 and 15, which avoids art increase in height h of the coil endsor width of the coil ends in the radial direction thereof.

In the three-phase stator windings 20 of the first embodiment, thewinding 30 of each phase per pole of the rotor is disposed in two of theslots 14 and 15. In other words, a total number of the slots per pole ofthe rotor of the stator windings 20 which are located adjacentcontinuously to each other in the circumferential direction is 3×2=6.The coil wire 30 is, thus, disposed in two of the slots 14 or 15 whichare located six slots away from each other in the circumferentialdirection. Accordingly, in order to avoid the interference between thewires 30 extending outside the circumferentially adjacent slots usingthe crank portion 44 at the middle of the wire 30, the turned portion 42is preferably designed to have the six (3×2) steps and one crankportion, as in the first embodiment.

In the first embodiment, the wire 30, as described above, has the sixsteps and the one crank portion formed on each of the axially isopposite coil ends of the stator core 12, thereby decreasing the heightand radial width of the coil end.

Next, how to winding the stator windings 20 will be described below withreference to FIGS. 6 to 8. In FIGS. 6 to 8, the total numbers of polesof the rotor 60 and the slots of the stator care 12 are decreased forbrevity of explanation. Assuming that the slots 14 and 15 are paired foreach phase, the four pairs of the slots 14 and 15 are, as illustrated inFIG. 7, formed in the stator core 12 at an interval of 90°. The pairs ofthe slots 14 and 15 of the different phases are, therefore, formed at aninterval of 30°. In the slots 14 and 15, a total of the eight in-slotportions 40 of the four wires 30 are disposed. Locations within the slot14 of each pair where the wires 30 are disposed are numbered from one(1) to four (4) radially from outside to inside the slot 14. Locationswithin the slot 15 of each pair where the wires 30 are disposed arenumbered from five (5) to eight (8) radially from outside to inside theslot 15.

In FIG. 8, winding specifications of the stator winding 20 of one phasewill be described. In FIG. 8, for example, “(1-4)” represents thewinding 30 to be disposed in the location 4 of #1 in FIG. 7. Asillustrated in FIG. 8, the wires disposed in the eight locations, asshown blow, of the slots 14 and 15 are joined continuously to foam eightgroups. The wires in the locations (1-1) and (1-5) are connected to theinput portion 50 (see FIG. 4). The stator winding 20 of one phase hastwo winding ends in the location (4-1) and (4-5) as neutral points 52(see FIG. 4). A total of the six neutral points 52 of the threephase-stator windings 20 are collected at one location, as illustratedin FIG. 4. In other words, the six neutral points 52 of the three-phasestator windings 20 of the first embodiment are star-connected.

(Group 1) (1-1)-(2-2)-(3-1)-(4-2) (Group 2) (1-2)-(2-1)-(3-2)-(4-1)(Group 3) (1-3)-(2-4)-(3-3)-(4-4) (Group 4) (1-4)-(2-3)-(3-4)-(4-3)(Group 5) (1-5)-(2-6)-(3-5)-(4-6) (Group 6) (1-6)-(2-5)-(3-6)-(4-5)(Group 7) (1-7)-(2-8)-(3-7)-(4-8) (Group 8) (1-8)-(2-7)-(3-8)-(4-7)

The continuing wires of the eight groups are connected as follow. Thewires (1-2) and (4-3), the wires (1-3) and (4-2), the wires (1-4) and(4-8), the wires (1-6) and (4-7), the wires (1-7) and (4-6), the wires(1-8) and (4-4) are connected respectively to form a pair of statorwindings (#1) and (#2) joined in parallel by the continuing wires 30, asindicated by a broken line and a solid line in FIG. 8 which extend fromthe input portion 50 to the neutral points 52. Similarly, the othertwo-phase windings 20 each form a pair of the stator windings connectedin parallel through the wires 30 continuing from the input portion 50 tothe neutral points 52. Joints 54 of the wires (1-4) and (4-8) and thewires (1-8) and (4-4) for three phases are denoted by numeral 54 in FIG.4.

Stator Winding #1 (INPUT PORTION)-(GROUP 1)-(GROUP 3)-(GROUP 8)-(GROUP6)-(NEUTRAL POINT) Stator Winding #2 (INPUT PORTION)-(GROUP 5)-(GROUP7)-(GROUP 4)-(GROUP 2)-(NEUTRAL POINT)

The wires 30 continuing over the entire circumference of the stator core12 to define the stator windings for one phase from the input portion 50to the neutral point 52, thereby minimizing electrical joints ascompared with the case where known segment conductors are weldedelectrically to form stator windings continuing from the input portion50 to the neutral point 52. This results in a decrease in manufacturingcost of the stator windings 20 and also minimizes poor electricconnections of the stator windings 20.

In the first embodiment, the radial width of the coil ends is decreased,so that the coil ends do not hung over outward radially, thus enablingthe neutral points 52 to be disposed radially outside the coil ends.

Second Embodiment

The second embodiment of the invention is illustrated in FIG. 9. Thesame reference numbers are attached to the same parts as in the firstembodiment.

The wire 70 of the second embodiment, like in the first embodiment, hasformed on a substantially middle of a turned portion 74 a crank portion76 which is not twisted. Protruding sections of the turned portion 74protruding outside the stator core 12 from the slots 14 and 15 havesteps 78 oriented to the slots, through which in-slot portions 72extend, along the end surface 13 of the stator core 12. However, thewire 70 of the second embodiment has a straight portion between thecrank portion 76 at the middle of the turned portion 74 and each of thesteps 78 fanned on the protruding portions and does not have any steps.

In the structure of the wire 70, the length of the base of a triangle,as defined by the wire 70 protruding from the slots 14 and 15 is smallerthan the interval between two of the slots 14 or 15 in which the wire 70is disposed, thus resulting in a decrease in height h of the coil end.

Third Embodiment

In the above embodiments, the stator of the rotary electric machine inwhich the wires 30 and 70 of the stator windings 20 are formed by theconductors 32 made of copper was explained. In contrast, the wires 30and 70 of this embodiment are made of aluminum. Aluminum is materialwhich is greater in electric resistance than copper. However, the shapeof the wires protruding from the stator core is decreased as a whole bynarrowing the interval between the protruding sections of the turnedportion further, thus resulting in a decrease in electric resistance ofthe whole of the stator windings. This permits the electric resistanceof the whole of the stator windings to be substantially equivalent tothat of the stator windings of the stator of the conventional rotaryelectric machine even if the wires 30 and 70 are made of aluminum. Theease with which the wires are machined may be facilitated by forming theconductors 32 by aluminum.

FOURTH EMBODIMENT

The structure of a rotary electric machine 410 of the fourth embodimentis illustrated in FIG. 10. The rotary electric machine 410 of thisembodiment is equipped with a housing 410 made by joining two bottomedcylindrical housings 410 a and 410 b at openings thereof, a rotor 402secured to a rotary shaft 420 supported by the housing 410 throughbearings 510 and 511 to be rotatable, and a stator 403 secured to thehousing 410 at a location surrounding the rotor 402 within the housing410.

The rotor 402 has a plurality of magnets disposed on an outer peripherythereof facing an inner periphery of the stator 403 to define magneticpoles different alternately in a circumferential direction thereof. Thenumber of the magnetic poles of the rotor 402 depends upon the type ofthe rotary electric machine and should not be limited thereto. In thisembodiment, the eight-pole (4 N-poles and 4 S-poles) rotor 402 is used.

The stator 403 has a structure equipped with a three-phase coil 404, asillustrated in FIG. 11, made up of a plurality of phase windings and astator core 430, as illustrated in FIG. 12.

The stator core 430 is, as illustrated in FIG. 12, of an annular shapewhich has a plurality of slots 431 formed in an inner periphery thereof.The slots 431 are formed to have a depth-wise direction coincident witha radial direction of the stator core 430.

The slots 431 are formed in the stator core 430 two for each of poles ofthe rotor 402 for each phase. Specifically, 8×3×2=48 slots 431 areformed.

The stator core 430 is made up of 24 core segments 432, as illustrate inFIG. 13, arrayed in a circumferential direction thereof. The coresegment 432 defines one of the slots 431 and is so formed as to have ashape (teeth 432 a extending in the radius direction and a core back 432b supporting the teeth 432 a) which define two of the slots 431 alongwith left and right adjacent ones of the core segments 432.

The core segment 432 is made of a stack of a plurality of 410 magneticsteel sheets having a thickness of 0.3 mm. An insulating sheet isinterposed between adjacent two of the magnetic steel sheets. The statorcore 430 may alternatively be made of a stack of typically known metalsheets and insulating films.

The coil 404 is formed by winding a plurality of stator winding wires440 in a given winding manner. The stator winding wires 440 forming thecoil 404 are, as illustrated in FIG. 14(A), each made of a copperconductor 441 and an insulating film 442 which is wrapped about theouter surface of the conductor 441 and consists of an inner layer 442 aand an outer layer 442 b. A total thickness of the insulating film 442(including thicknesses of the inner and outer layers 442 a and 442 b) is100 μm to 200 μm. Such a great thickness of the insulating film 442 madeup of the inner layer 442 a and the outer layer 442 b eliminates theneed for insulating the stator winding wires 440 electrically from eachother with insulating sheet interposed between the stator winding wires440, but insulating sheet 405 may be interposed between the wires.

Further, the stator winding wire 440 of the coil 404, as illustrated inFIG. 14(B), may have a fusing material 448 made of epoxy resin withwhich the outer periphery of the insulating film 442 made up of theinner layer 442 a and the outer layer 442 b is covered. The fusingmaterial 448, thus, melts earlier than the insulating film 442 whensubjected to the heat generated in the rotary electric machine, so thatthe stator winding wires 440 disposed in the same slot 431 are thermallybonded to each other through the fusing materials 448. The statorwinding wires 440 in the same slot 431, therefore, will change into aone-piece winding, thus resulting in an increase in mechanical strengthof the stator winding wires 440 in the slots 431.

The coil 404 is, as shown in FIG. 15, fabricated by three phase windings(U1, U2, V1, V2, W1, W2). More specifically, a stator winding 440 adefining a U1-phase and a stator winding 440 b defining a U2-phase arejoined in series. A stator winding 440 c defining a U2-phase and astator winding 440 d defining a U1-phase are joined in series. Thestator windings 440 a and 440 b axe connected to the stator windings 440c and 440 d in parallel to form a U-phase winding. Similarly, a V-phaseand a W-phase winding are made in the same manner.

The stator winding wires 440 making the coil 404 are wave-wound on aninner circumferential side of the stator core 430 in the circumferentialdirection. The stator winding wire 440 has straight in-slat portions 443to be disposed in the slots 431 of the stator core 430 and turnedportions 444 each of which connects between adjacent two of the in-slotportions 443. The in-slot portions 443 arc accommodated in everypredetermined number of the slots 431 (every 3 phases×2=6 slots in thisembodiment). The turned portions 444 project from axially-opposed endsof the stator core 430.

In the coil 404, the turned portions 444 are formed on axial oppositesides of the stator core 430. The turned portion 444 has formed on asubstantially middle thereof a crank portion which does not twist.

As illustrated in FIG. 16, all protruding sections of the turned portion444 protruding outside the stator core 430 from the slots 431 have steps444D extending along the end surfaces of the stator core 430. in FIG.16, the steps 444D are disposed away from the stator core 430, buthowever, may be placed in contact abutment with the stator core 430. Theturned portions 444 axe formed stepwise which have a plurality of stepsparallel to the end surfaces of the stator core 430, thus avoiding theinterference of the stepwise turned portions 444 of the stator windingwires 440 with the stator winding wires 440 protruding from thecircumferentially adjacent slots 431. This avoids an increase in heightof the coil ends or width of the coil ends in the radial directionthereof for eliminating the interference between the stator windingwires 440 protruding from the circumferentially adjacent slots 431. Thisresults in a decrease in height and width of the coil ends to avoid theradially outward overhanging of the coil 404.

The stepwise turned portion 444 has the crank portion 444A at a sectionthereof which is farthest away from the stator core 430 (i.e. thehighest portion). The crank portion 444A is formed in parallel to theend surface of the stator core 430. The amount of offset of the crankportion 444A in the radial direction of the stator core is substantiallywithin the width of the stator winding wire 440. Specifically, theamount of offset is 1.0 to 1.3 times greater than the width of thestator core 440. The turned portion 444 of the stator winding wire 440has stepwise sides opposed to each other across the crank portion 444A.The crank portion 444A is laid to vertically overlap the turned portion444 of the stator winding wire 440 disposed in the adjacent slot 431.

The turned portion 444 is formed to have a four-step shape.Specifically, the turned portion 444 has the three steps 444B to 444Dwhich extend parallel to the end surface of the stator core 430 and areformed at locations different in the axial direction of the stator core430. The steps 444B to 444D extend parallel to the end surface of thestator core 430, but however, need not be parallel thereto exactly. Thesteps 444B to 444D may be parallel within a range in which the height ofthe coil ends is permitted to be lowered. In this embodiment, except thecrank portion 444A which is farthest from the end surface of the statorcore 430, the step 444C which is farthest therefrom will be referred toas the uppermost step 444B. The step 444C which is second farthesttherefrom will be referred to as the second step 444C. The step 444Dwhich is closest to the end surface of the stator core 430 will bereferred to as the third step 444D. The length of a portion of each ofthe uppermost step 444B, the second step 444C, and the third step 444Dwhich extends parallel to the end surface of the stator core 430 issmaller than or equal to the interval between circumferentially adjacenttwo of the slots 431.

In this embodiment, if the distance between the crank portion 444A andthe uppermost step 444B is defined as l₁, the distance between theuppermost step 444B and the second step 444C is defined as l₂, and thedistance between the second step 444C and the third step 444D is definedas l₃, a relation of l₁>l₂=l₃. For example, l₁ is 1.02 to 1.3 timesgreater than l₂. The distances l₁, l₂, and l₃ may meet a relation ofl₁≧l₂=l₃. The height of each of the steps 444B to 444D is substantiallyequivalent to the height of the stator winding wire 440. Specifically,such a height is 1.0 to 1.3 times greater than that of the statorwinding wire 440. In this embodiment, the distances between the crankportion 444A and the steps 444B to 444D of the turned portion 444 are,as schematically illustrated in FIG. 16, defined based on the backsurfaces thereof behind the stator core 430. In this embodiment, thestepwise formation of the turned portions 444 permits the turnedportions 444 to be laid to overlap each other without any clearancestherebetween, thereby winding the turned portions 444 tightly.

Further, in this embodiment, of the distances between the crank portion444A and the steps 444B to 444D of the turned portion 444, the distancel₁ between the crank portion 444A and the uppermost step 444B is greaterthan the distances l₂ and l₃ between the steps 444B to 444D, therebyeliminating the interference of the crank portion 444 of one of theturned portions 444 with the stator winding wire 440 having the otherturned portions 444 when they are laid to overlap each other. Theinclination of a joint between the end of the crank portion 444A and theend of the uppermost step 444B is greater than that of a joint betweenthe end of the uppermost step 444B and the second step 444C.

When the distance l₁ between the crank portion 444A and the uppermoststep 444B is smaller than the distances l₂ and l₃ between the steps 444Bto 44-4D (i.e., l₁<l₂=l₃), it will, as illustrated in FIG. 17, causecorners of rectangular sections of the stator winding wires 440 formingthe turned portions 444 extending one over another to make a contact orinterference therebetween.

Although not limited, the distance between the third step 444D of theturned portion 444 and the end surface of the stator core 430 ispreferably equivalent to about the height of the stator winding wire440.

The coil 40 is designed so that the end of each of the stator windingwires 440 making the coil 404 protrudes radially outward within theheight of the coil ends defined by the turned portions 444 projectingfrom the stator core 430. The ends of the respective stator windingwires 440 that are on the side of the neutral points protrude radiallyoutward at a location higher than the other ends thereof.

Next, the winding of the stator cores 440 forming the coil 404 in thisembodiment will be described below in detail using FIGS. 18 to 23.

The coil 404 of this embodiment is made up of the three-phase windings(U1, U2, V1, V2, W1, and W21 two pairs for each phase. FIG. 18illustrates how to connect the three-phase windings. Slot numbers inFIG. 18 are as follows. The slot number 1 indicates one of the slots 431in which one of the in-slot portions 443 which is closest to one of theends of the U1-phase stator winding wire 440 on the side of the neutralpoint is disposed. The slot numbers 2, 3, 4, . . . convenientlyindicates the slots 431 arrayed in the circumferential direction inwhich the stator winding wires 440 are wound. FIG. 19 demonstrates onlythe stator winding wires 440 forming the U-phase winding (i.e., the U1-and U2-phase windings, as illustrated in FIG. 18. In FIGS. 18 to 19,lines extending straight vertically indicate the in-slot portions 443.Lines extending obliquely upward or downward indicate the turnedportions 444.

FIG. 20 is a development view of the coil 404 of this embodiment. Thejoint of the ends of the windings 440 a and 440 c is the neutral point.The joint of the ends of the windings 440 b and 440 d is a phaseterminal.

The respective phase windings are identical in connection thereof. Howto wind the stator winding wires 440 of the coil 404 will be describedbelow with reference to the U-phase winding. FIG. 21 illustrates thelayout of connections of the stator winding wires 440 of the U-phase.FIG. 21( a) illustrates the layout of connections of wires 440 a and 440b. FIG. 21( b) illustrates the layout of connections of wires 440 c and440 d. FIG. 22 illustrates positional relations between the wires 440 aand 440 b and between the turned portions 444 thereof in the depthwisedirection of the slots 431. FIG. 23 illustrates positional relationsbetween the wires 440 c and 440 d and between the turned portions 444thereof in the depthwise direction of the slots 431.

The connection between the stator winding wires 440 a and 440 b will bedescribed below with reference to FIGS. 21( a) and 22. The stator 402has eight poles. The slots 431 in which the U-phase stator winding wires440 are illustrated as sixteen (16) slots 440 a-1, 440 a-2, . . . 440a-8, 440 b-1, 440 b-2, . . . and 440 b-8. Within the slot 431, the eight(8) in-slot portions 443 are laid to overlap each other in the depthwisedirection. Locations in the slot 431 in the depth-wise direction thereofwhere the in-slot portions 443 are disposed are assigned with numerals8, 7, 6, . . . , and 1, respectively.

The stator winding wires 440 a and 440 b are joined in series. The endof the stator winding wire 440 a-1 is connected to the neutral point.The end of the stator winding wire 440 b-1 is joined to the wire 440 dto make a connection with the U-phase terminal.

The stator winding wire 440 a has the in-slot portion 443 which isdisposed at the first location in the slot 440 a-1 and is closest to theneutral position. The stator winding wire 440 b has the in-slot portion443 which is disposed at the first location in the slot 440 b-1 and isclosest to the end of the wire 440 b.

The in-slot portion 443 of the stator winding wire 440 a connecting withthe adjacent one disposed in the slot 440 a-1 through the turned portion444 connects with the turned portion 444I that is one of the turnedportion 444 lying on the end of the stator core 430 (will also bereferred to as a lower end below) which is opposite the end of thestator core 430 (will also be referred to an upper end below) from whichthe end protrudes and connects with the neutral point and enters thesecond location in the slot 440 a-2. In other words, the lower turnedportion 444I connects between the in-slot portion 443 at the firstlocation in the slot 440 a-1 and the in-slot portion 443 at the secondlocation in the slot 440 a-2 on the lower end of the stator core 430.

The in-slot portion 443 of the stator winding wire 440 a connecting theadjacent one disposed in the slot 440 a-2 connects with the upper turnedportion 444II and enters the first location in the slot 440 a-3. Inother words, the upper turned portion 444II connects between the secondlocation in the slot 440 a-2 and the first location in the slot 440 a-3on the upper end of the stator care 430.

The in-slot portion 443 of the stator winding wire 440 a connecting withthe adjacent one disposed in the slot 440 a-3 connects with the turnedportion 444III enters the second location in the slot 440 a-4. Asapparent from the above, the lower turned portions 444III connectsbetween the first location in the slot 440 a-3 and the second locationin the slot 440 a-4 on the lower end of the stator core 430.

The in-slot portion 443 of the stator winding wire 440 b connecting withthe adjacent one disposed in the slat 440 b-1 connects with the lowerturned portion 44II that is one of the turned portion 444 lying on lowerend of the stator core 430 and enters the second location in the slot440 b-2. In other words, the turned portion 444II connects between thefirst location in the slot 440 b-1 and the second location in the slot440 b-2 on the lower end of the stator core 430.

The in-slot portion 443 of the stator winding wire 440 b connecting withthe adjacent one disposed in the slot 440 b-2 connects with the turnedportion 444III and enters the first location in the slot 440 b-3. Inother words, the upper turned portion 444III connects between the secondlocation in the slot 440 b-2 and the first location in the slot 440 b-3on the upper end of the stator core 430.

The in-slot portion 443 of the stator winding wire 440 b connecting withthe adjacent one disposed in the slot 440 b-3 connects with the turnedportion 444IV and enters the second location in the slot 440 b-4. Inother words, the lower turned portions 444IV connects between the firstlocation in the slot 440 b-3 and the second location in the slot 440 b-4on the lower end of the stator core 430.

As apparent from the above, the two stator winding wires 440 a and 440 bare such that the upper turned portions 444II to 444VII lying above theupper end of the stator core 430 connect between the adjacent second andfirst locations for the in-slot portion 443, while the lower turnedportions 444I to 44VIII lying below the lower end of the stator core 430connect between the adjacent the first and second locations for thein-slot portion 443. In this manner, the in-slot portions 443 of the twostator winding wires 440 a and 440 b are disposed from the slot 440 a-1to the slot 440 a-8 and from the slot 440 b-1 to the slot 440 b-8 alongthe circumference of the stator core 340. In the slots 440 a-8 and 440b-8, the in-slot portions 443 of the stator winding wire 440 a lie atthe second locations.

The in-slot portions 443 of the stator winding wires 440 a and 440 bnext to the ones at the second locations in the slots 440 a-8 and 440b-8 are disposed at the third locations in the slots 440 a-1 and 440b-1, respectively. In other words, the upper turned portions 444VIII and444I above the upper end of the stator core 430 connect between thesecond locations in the slots 440 a-8 and 440 b-8 and the thirdlocations in the slots 440 a-1 and 440 b-1 on the upper end of thestator core 430. Specifically, after being wound one time around thecircumference of the stator core 430, the connected wires arc wound andshifted radially inward by one layer.

The in-slot portion 443 of the stator winding wire 440 a connecting withthe ones at the third location of the slot 440 a-1 connects with thelower turned portion 444I and enters the fourth location in the slot 440a-2. In other words, the lower turned portions 444I connects between thethird location in the slot 440 a-1 and the fourth location in the slot440 a-2 on the lower end of the stator core 430

The in-slot portion 443 of the stator winding wire 440 a connecting withthe adjacent one disposed in the slot 440 a-2 connects with the upperturned portion 444II on the upper end of the stator core 430 and entersthe third location in the slot 440 a-3. In other words, the upper turnedportions 444II connects between the fourth location in the slot 440 a-2and the third location in the slot 440 a-3 on the upper end of thestator core 430.

The in-slot portion 443 of the stator winding wire 440 a connecting withthe adjacent one disposed in the slot 440 a-3 connects with the turnedportion 444III on the lower end of the stator core 430 and enters thefourth location in the slot 440 a-4. In other words, the turned portions444III connects between the third location in the slot 440 a-3 and thefourth location, in the slot 440 a-4 on the lower end of the stator core430.

The stator winding wire 440 b connecting with the third location of theslot 440 b-1 connects with the lower turned portion 444II and enters thefourth location in the slot 440 h-2. In other words, the lower turnedportions 444II connects between the third location in the slot 440 b-1and the fourth location in the slot 440 b-2 on the lower end of thestator core 430.

The in-slot portion 443 of the stator winding wire 440 b connecting withthe adjacent one in the slot 440 b-2 connects with the upper turnedportion 444III on the upper end of the stator core 430 and enters thethird location in the slot 440 b-3. In other words, the upper turnedportions 444III connects between the fourth location in the slot 440 b-2and the third location in the slot 440 b-3 on the upper end of thestator core 430.

The in-slot portion 443 of the stator winding wire 440 b connecting withthe adjacent one in the slot 440 b-3 connects with the lower turnedportion 444W and enters the fourth location in the slot 440 b-4. Inother words, the lower turned portions 444IV connects between the thirdlocation in the slot 440 b-3 and the second location in the slot 440 b-4on the lower end of the stator core 430.

As apparent from the above, the two stator winding wires 440 a and 440 bare such that the upper turned portions 444II to 444VII lying above theupper end of the stator core 430 connect between the adjacent in-slotportions 443 in the third and fourth locations, while the turnedportions 444I to 444VIII lying blow the lower end of the stator core 430connect between the adjacent in-slot portions 443 at the third andfourth locations. In this manner, the in-slot portions 443 of two statorwinding wires 440 a and 440 b are disposed from the slot 440 a-1 to theslot 440 a-8 and from the slot 440 b-1 to the slot 440 b-8 along thecircumference of the stator core 430. In the slots 440 a-8 and 440 b-8,the in-slot portions 443 of the stator winding wire 440 a lie at thefourth locations.

The in-slot portions 443 of the stator winding wires 440 a and 440 bnext to the ones at the fourth locations in the slots 440 a-8 and 440b-8 are disposed at the fifth locations in the slots 440 a-1 and 440b-1, respectively. In other words, the upper turned portions 444VIII and444I connect between the fourth locations in the slots 440 a-8 and 440b-8 and the fifth locations in the slots 440 a-1 and 440 b-1 above theupper end of the stator core 430. Specifically, after being wound onetime around the circumference of the stator core 430, the connectedwires are wound and shifted radially inward by one layer.

The stator winding wire 440 a connecting with the fifth location of theslot 440 a-1 connects with and enters the sixth location in the slot 440a-2 through the lower turned portion 444I. In other words, the lowerturned portions 444I connects between the fifth location in the slot 440a-1 and the sixth location in the slot 440 a-2 on the lower end of thestator core 430.

The in-slot portion 443 of the stator winding wire 440 a lying adjacentthe one in the slot 440 a-2 connects with the upper turned portion 444IIand enters the fifth location in the slot 440 a-3. In other words, theupper turned portions 444II connects between the sixth location in theslot 440 a-2 and the fifth location in the slot 440 a-3 on the upper endof the stator core 430.

The in-slot portion 443 of the stator winding wire 440 a lying adjacentthe one in the slot 440 a-3 connects with the lower turned portion444III and enters the sixth location in the slot 440 a-4. In otherwords, the lower turned portions 444III connects between the fifthlocation in the slot 440 a-3 and the sixth location in the slot 440 a-4on the lower end of the stator core 430.

The stator winding wire 440 b connecting with the fifth location of theslot 440 b-1 connects with the lower turned portion 444II and enters thesixth location in the slot 440 b-2. In other words, the lower turnedportions 444II connects between the fifth location in the slot 440 b-1and the sixth location in the slot 440 b-2 on the lower end of thestator core 430.

The in-slot portion 443 of the stator winding wire 440 b lying adjacentthe one in the slot 440 b-2 connects with the upper turned portion444III and enters the fifth location in the slot 440 b-3. In otherwords, the upper turned portion 444III connects between the sixthlocation in the slot 440 b-2 and the fifth location in the slot 440 b-3on the upper end of the stator core 430.

The in-slot portion 443 of the stator winding wire 440 b lying adjacentthe one in the slot 440 b-3 connects with the lower turned portion 444IVand enters the sixth location in the slot 440 b-4. In other words, theturned portion 444IV connects between the fifth location in the slot 440b-3 and the sixth location in the slot 440 b-4 on the lower end of thestator core 430.

As apparent from the above, the two stator winding wires 440 a and 440 bare such that the upper turned portions 444II to 444VII lying above theupper end of the stator core 430 connect between the adjacent in-slotportions 443 at the fifth and sixth locations, while the lower turnedportions 444I to 444VIII lying below the lower end of the stator core430 connect between the adjacent in-slot portions 443 at the fifth andsixth locations. In this manner, the stator winding wires 440 a and 440b extend from the slot 440 a-1 to the slot 440 a-8 and from the slot 440b-1 to the slot 440 b-8 along the circumference of the stator core 430.In the slots 440 a-8 and 440 b-8, the in-slot portions 443 of the statorwinding wire 440 a lie at the sixth locations.

The in-slot portions 443 of the stator winding wires 440 a and 440 bnext to the ones at the sixth locations in the slots 440 a-8 and 440 b-8are disposed at the seventh locations in the slots 440 a-1 and 440 b-1,respectively. In other words, the upper turned portions 444VIII and 444Iconnect between the sixth locations in the slots 440 a-8 and 440 b-8 andthe seventh locations in the slots 440 a-1 and 440 b-1 on the upper endof the stator core 430. Specifically, after being wound one time aroundthe circumference of the stator core 430, the connected wires are woundand shifted radially inward by one layer.

The stator winding wire 440 a connecting with the seventh location ofthe slot 440 a-1 connects with the lower turned portion 444I and entersthe eighth location in the slot 440 a-2. In other words, the lowerturned portions 444I connects between the seventh location in the slot440 a-1 and the eighth location in the slot 440 a-2 on the lower end ofthe stator core 430.

The in-slot portion 443 of the stator winding wire 440 a lying adjacentthe one in the slot 440 a-2 connects with the upper turned portion 444IIand enters the seventh location in the slot 440 a-3 in other words, theupper turned portions 444II connects between the eighth location in theslot 440 a-2 and the seventh location in the slot 440 a-3 on the upperend of the stator core 430.

The in-slot portion 443 of the stator winding wire 440 a lying adjacentthe one in the slot 440 a-3 connects with the lower turned portion444III and enters the eighth location in the slot 440 a-4. In otherwords, the lower turned portion 444III connects between the seventhlocation in the slot 440 a-3 and the eighth location in the slot 440 a-4on the lower end of the stator core 430.

The in-slot portion 443 of the stator winding wire 440 b lying adjacentthe one at the seventh location of the slot 440 b-1 connects with thelower turned portion 444II and enters the eighth location in the slot440 b-2. In other words, the lower turned portion 444II connects betweenthe seventh location in the slot 440 b-1 and the eighth location in theslot 440 b-2 on the lower end of the stator core 430.

The in-slot portion 443 of the stator winding wire 440 b lying adjacentthe one in the slot 440 b-2 connects with the upper turned portion444III and enters the seventh location in the slot 440 b-3. In otherwords, the upper turned portion 444III connects between the eighthlocation in the slot 440 b-2 and the seventh location in the slot 440b-3 on the upper end of the stator core 430.

The in-slot portion 443 of the stator winding wire 440 b lying adjacentthe one in the slot 440 b-3 connects with the lower turned portion 444IVand enters the eighth location in the slot 440 b-4. In other words, thelower turned portion 444IV connects between the seventh location in theslot 440 b-3 and the eighth location in the slot 440 b-4 on the lowerend of the stator core 430.

As apparent from the above, the two stator winding wires 440 a and 440 hare such that the upper turned portions 444II to 444VII lying above theupper end of the stator core 30 connect between the adjacent in-slotportions 443 at the seventh and eighth locations, while the lower turnedportions 441 to 44VIII lying blow the lower end of the stator core 430connect between the adjacent in-slot portions 443 at the seventh andeighth locations. In this manner, the stator winding wires 440 a and 440b extend from the slot 440 a-1 to the slot 440 a-8 and from the slot 440b-1 to the slot 440 b-8 along the circumference of the stator core 430.In the slots 440 a-8 and 440 b-8, the in-slot portions 443 of the statorwinding wire 440 a lie at the eighth locations.

The in-slot portions 443 disposed in the slots 440 a-8 and 440 b-8 arejoined. In the manner, the stator winding wires 440 a and 440 b arewound around the stator core 430.

Next, connections of the stator winding wires 440 c and 440 d are shownin FIGS. 21( b) and 23 which are substantially the same as those of thestator winding wires 440 a and 440 b, and explanation thereof in detailwill be omitted here.

In this embodiment, the distances between the crank portion 444A and thesteps 444B to 444D of the turned portions 444 meet a relation ofl₁>l₂=l₃ (or l₁≧l₂=l₃), thereby avoiding the interference between thestator winding wires 440 having the different turned portions 444 andthus enabling the turned portions 444 to overlap each other without anyclearances arising from the interference. This enables the turnedportions 444 to be wound tightly.

In this embodiment, the distance between the crank portion 444A and theuppermost step 444B is long, thereby avoiding the interference betweenthe turned portions overlapping each other.

Other Embodiments

In the above embodiments, the stator of the rotary electric machineworking as the electric motor and the electric generator is explained.The stator of the above embodiments may be used as a stator of therotary electric machine working as either one of the electric motor andthe electric generator.

In the above embodiments, the wire continuing over the entirecircumference of the stator core 12 defines the stator winding for eachphase, but however, the stator winding may alternatively be made bywelding U-shaped segment conductors to each other and forming the crankportion and the steps, as described in the first and second embodiments.

The stator windings are not only limited to the use for three phases,but may be used for multi-phase. If the number of stator windings is k,and the number of slots for each phase per pole of the stator is n, thenumber of the steps of the turned portion of the wire is preferably k×n.

In the above embodiments, the crank portion is formed substantially atthe middle of the turned portion, but does not needs be formed at themiddle of the turned portion as long as the steps are formed at sectionsof the turned portion which protrude from the slots.

In the above embodiments, the structure in which the rotor is disposedinside the inner circumference of the stator so as to face the stator onthe side of the inner circumference is described, but however, thestructure in which the rotor is disposed outside the outer circumferenceof the stator so as to face the stator on the side of the outercircumference.

In the above embodiments, the three-phase stator windings 20 arestar-connected, but however, may be delta-connected in the form of anannular shape.

As described above, the invention is not limited to the aboveembodiments and can be embodied in various ways without departing fromthe principle of the invention.

1. A stator for a rotary electric machine equipped with a stator corehaving a plurality of slots in a circumferential direction and statorwindings which are made of wire and disposed in the slots characterizedin that said stator windings include in-slot portions disposed in theslots different in the circumferential direction and turned portionsconnecting said in-slot portions outside the slots, and steps whichextend along an end surface of said stator core are formed at sectionsof the turned portions protruding from said slots.
 2. A stator for arotary electric machine as set forth in claim 1, characterized in thatthe steps which extend along the end surface of said stator core areformed at all the sections of said turned portion protruding from saidslots.
 3. A stator for a rotary electric machine as set forth in claim1, characterized in that a length of the protruding sections of saidturned portions along the end surface of the stator core is smaller thanor equal to an interval between the slots adjacent in thecircumferential direction.
 4. A stator for a rotary electric machine asset forth in claim 1, characterized in that said turned portions areshaped stepwise to have the steps, which are parallel to the end surfaceof said stator core, in an axial direction of said stator core.
 5. Astator for a rotary electric machine as set forth in claim 4,characterized in that a length of all said steps parallel to the endsurface of said stator core is smaller than or equal to an intervalbetween the slots adjacent in the circumferential direction.
 6. A statorfor a rotary electric machine as set forth in claim 4, characterized inthat if the number of phases of said stator windings is k, and thenumber of said slots for each phase per pole of a rotor having aplurality of magnetic poles different alternately in the circumferentialdirection is n, the number of said steps formed at the turned portion isk×n.
 7. A stator for a rotary electric machine as set forth in claim 1,characterized in that the turned portions have a crank-shaped crankportion formed at a location farthest away from said stator core.
 8. Astator for a rotary electric machine as set forth in claim 7,characterized in that the crank portion is formed in parallel to the endsurface of said stator core.
 9. A stator for a rotary electric machineas set forth in claim 7, characterized in that said crank portion isshifted in a radial direction of said stator core by a width of saidwire.
 10. A stator for a rotary electric machine as set forth in claim7, characterized in that each of said turned portions is laid to overlapa circumferentially adjacent one of said turned portions in an axialdirection,
 11. A stator for a rotary electric machine as set forth inclaim 7, characterized in that said turned portion is shaped stepwise tohave a plurality of steps in an axial direction of said stator corewhich are in parallel to the end surface of said stator core, and anaxial distance between the crank portion and an uppermost step that isone of said steps defining a stepwise shape which is farthest from saidstator core in the axial direction is longer than an axial distancebetween said steps.
 12. A stator for a rotary electric machine as setforth in claim 11, characterized in that said crank portion is laid toaxially overlap said uppermost step of a circumferentially adjacent oneof said turned portions.
 13. A stator for a rotary electric machine asset forth in claim 11, characterized in that distances between saidsteps of said turned portion is equivalent to a height of said wire. 14.A stator for a rotary electric machine as set forth in claim 1,characterized in that said wire has a rectangular section.
 15. A statorfor a rotary electric machine as set forth in claim 1, characterized inthat said wire is formed to continue over an entire circumference ofsaid stator core.
 16. A stator for a rotary electric machine as setforth in claim 1, characterized in that said wire has a conductor and aninsulating film wrapped about the conductor, the insulating film havinga thickness of 100 to 200 μm.
 17. A stator for a rotary electric machineas set forth in claim 16, characterized in that said insulating film hasan inner layer and an outer layer covering said inner layer, said outerlayer being lower in glass-transition temperature than said inner layer.18. A stator for a rotary electric machine as set forth in claim 16,characterized in that said wire has a fusing material covering an outerperiphery of said insulating film.
 19. A stator for a rotary electricmachine as set forth in claim 1, characterized in that said wire has anconductor made of aluminum.
 20. A rotary electric machine characterizedin that it includes the stator as set forth in claim 1 and a rotorforming magnetic poles different alternately in the circumferentialdirection.
 21. A stator for a rotary electric machine equipped with astator core having a plurality of slots in a circumferential directionand a stator windings which is made of wire and disposed in the slotscharacterized in that said Stator windings include in-slot portionsdisposed in the slots different in the circumferential direction andturned portions connecting said in-slot portions outside the slots, andall the turned portions have steps parallel to an end surface of saidstator core.